1. Field of the Invention
The present invention relates to a plastic-substrate liquid crystal display (LCD) device which utilizes plastic substrates as substrates for sandwiching liquid crystals.
2. Description of the Prior Art
There is conventionally provided a plastic-substrate LCD device shown in FIG. 3 as a LCD device of the above-mentioned type. This plastic-substrate LCD device is provided with a pair of acrylic (or epoxy) plastic substrates 103 for sandwiching liquid crystals 110. Each plastic substrate (0.1 to 0.5 mm thick) 103 has, on its inner and outer faces, hard coats 102, 104 (2 to 6 .mu.m) made of an organosilane-, acrylic-, melamine-, urethane-related or like organic resin, through the dipping and baking. Inside the hard coat 104 there are provided an undercoat (100 to 600A thick) 105 made of SiOx and an indium tin oxide (ITO) electrode 106 made of indium tin oxide, in this order, by the method of spattering deposition. Further provided inside of this by a known method are a top coat (upper protective coat) 107 for protecting the ITO electrode 106 and an orientation coat 108 for orienting the liquid crystals 110. In addition, represented by numeral 109 is a sealing material for sealing the liquid crystals 110, and by 101 is a polarizing plate.
In the above-described conventional plastic-substrate LCD device, it may occur in some cases that moisture which has been adsorbed in the plastic substrate 103 will emerge on the deposition surface of the substrate 103 (more precisely, of the hard coat 104) while the SiOx undercoat 105 and the ITO electrode 106 are subjected to spattering deposition. By this emergence, the deposition is obstructed such that the adhesion of the undercoat 105 and the ITO electrode 106 with respect to the substrate 103 is impaired. Also, since the inorganic-constituted SiOx undercoat 105 and ITO electrode 106 are provided in contact with the organic-constituted plastic substrate 103 and hard coat 104, there may occur some cracks to the undercoat 105 and the ITO electrode 106, disadvantageously, which can be attributed to difference in thermal expansion coefficient between organic and inorganic substances as well as to various strains of the substrate itself.